Wheels of various sorts have been used in the past for rollable support of a wide variety of household and domestic vehicles and devices including garbage carts, lawn and garden equipment, shopping carts, golf carts, children's tricycles, and outboard training wheels for juvenile sidewalk bicycles. Wire-spoke wheels have proved eminently suitable in these applications, but the search for less expensive designs has lead to the introduction of wheel discs made of plastic. However, a common problem with prior art plastic wheel centers has been the comparative radial weakness of the most economical configurations. A related difficulty has resided in warpage of the wheel disc and rim and the resultant wobbly tracking that has been exhibited by those designs employing deep, hollow spokes for strength-enhancement. An example o the configurations that are subject to this undesirable warpage and wobbly tracking is shown in U.S. Pat. No. De-239,619.